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How To Use A Cold Frame

By January 9, 2014 December 8th, 2015 Garden Planning, Uncategorized

What Is A Cold Frame?

A cold frame is a transparent cover that goes over your garden during the coldest months to protect your plants from adverse weather. They are used to extend the growing season. Cold frames also allow gardeners to grow hardy greens through the winter. Cold frames are primarily used for cold crops, not warm crops such as tomatoes and peppers! The growth rate of plants slows substantially in the coldest months to the point where harvesting will be minimal. However, the cold frames can “over-winter” your plants, or keep plants alive until the spring when they will come back quickly and rapidly as warm weather comes in March and April. Using a cold frame, you can often be eating salad from your garden before most people have planted their gardens in the spring!


Urban Farm Company Cold Frame Closed

Urban Farm Company Cold Frame Closed

Urban Farm Company Cold Frame Open

Urban Farm Company Cold Frame Open

Urban Farm Company Cold Frames

Urban Farm Company cold frames are made from UV-Resistant Piping arched over the gardens and connected to the outside of the garden bed. We use 6mm greenhouse plastic cut to size to completely enclose the garden bed. The plastic we use is much better than normal plastic: it’s UV resistant, has an anti-drip coating on the inside, and is specially designed for greenhouse growing. The plastic is weighed down on both long ends, and clipped to the frame on the short ends so it won’t blow off in the wind!

Our cold frames are intended to be left on the gardens all winter long. Half of the plastic can be lifted up and folded over the other half to access the garden for watering or harvesting, or for hot fall and spring days when the garden should be ventilated.

Leave your cold frame on from mid-October through mid to late April. Don’t take it off ALL winter! Vent the cold frame occasionally throughout the winter when daytime temperatures reach 70 degrees so your plants don’t over heat.  Continue to water your garden throughout the winter (every few weeks), whenever the soil is dry. Moist soil is critical for soil and plant health. Remove cold frame completely in May, after the last chance of frost.

How to put on your cold frame:

  • Place the cold frame plastic over the PVC frame. The 2’x4’ boards should lie parallel to the long side of the garden bed to weigh it down.
  • Fold the extra plastic around the short side of the garden bed like you are wrapping a present. Use the hand clamps to attach the greenhouse plastic to the garden bed.
  • Place a brick on the extra plastic on the ground to keep it from flapping up in the wind.

Planting your cold frame: Cold frames are best for cold season crops. Plant your cold season crops earlier in the spring and later in the fall than you would be able to without a cold frame. You can plant cold crops as early at March 15th in the spring and as late at September 15th in the fall.

To vent your cold frame:

  • Take the hand clamps off and remove the bricks.
  • Attach two hand clamps to the top of the PVC frame, one on each outer PVC pipe.
  • Roll the greenhouse plastic up around the 2’x4’ board and rest the board against the hand clamps to vent the cold frame.
  • If possible, vent the southern or western side of your cold frame.

To remove your cold frame:

  • Remove the hand clamps and bricks.
  • Fold up the short ends on the greenhouse plastic.
  • Roll the green house plastic around the 2’x4’ boards to neatly and store indoors for the summer months.
  • Use the PVC frame for a hail/shade protective cover or for pest netting!

Tip 1

Bricks, dark stones, and jugs of water will soak up heat during the day and release it throughout the cold nights.

Tip 2

You can add non-LED Christmas lights underneath the frame to keep them a little warmer and increase the growth rate. Lights can raise the temperature in your cold frame by 20 degrees.

Tip 3

Add another layer of floating row cover (Reemay or Agribon) to the inside of the cold frame directly above the plants. Ideally keep it off of the plants. See our Winter Post for more information.

Tip 4

 Apply mulch to your garden (straw or grass clippings are best). This will help keep your soil moist throughout the season and helps keep the soil a little bit warmer. 

Suggested Cold Season Crops To Grow Under Cold Frames

  • Spinach*
  • Kale*
  • Mache*
  • Scallions*
  • Carrots*
  • Claytonia*
  • Parsley
  • Bok Choy
  • Collards
  • Lettuce
  • Sorrel
  • Turnips
  • Parsnips
  • Micro Greens
  • Beets
  • Mustard
  • Radish
  • Arugula
  • Chard

* Hardiest vegetables

Here is your  Winter Crop Varieties document. Stay warm.


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  • Ruth says:

    My first experience with a cold frame was a great success, planting seeds in January (they didn’t germinate until February) then eating bountiful fresh salads every day starting the middle of March! Next time I am going to try something different: transplanting mature plants, like chard or kale, into the cold frame in the fall, so that I can harvest continuously from plants that already have a lot of growth; this will take advantage of the long-sun days of summer to build the plants, and will put less expectation on young plants to feed me when the hours of sunlight reach a winter low.

    • That’s a great idea. The key to eating substantial food into December under the cold frame is having your plants pretty large already by October. They won’t grow much more in the later months, but they will stay alive and ready for harvest under the cold frame. So transplants are a smart idea. Thanks!

  • Eileen Berry says:

    I did not get one radish, can I plant some now, and what kind would I buy to put in my garden???

  • Glinda says:

    Hello everybody, here every person is sharing such knowledge,
    therefore it’s good to read this web site, and I used to visit this webpage daily.

  • MegC says:

    Do you still have your winter post? They hyperlink is broken. Thank you!

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